Process of hardening and draw-tempering steel.



NIL $54,954, Patented-July l7. i900.

' G; DELAY. PRQGESS HF HARDENING AND DRAW 'TEMPERING STEEL.-

(Application filed Nov. 17, 1899.)

(No Model.)

6&57506 36%,

GUSTAVE DELAY, OF LE LOOLE, SlVITZERLAND.

PROCESS OF HARDENING AND DRAW-TEMPERING STEEL.

SPECIFICATION forming part of Letters Patent N 0. 654,054, dated July 17, 1900.

Serial No. 737,355. (No specimens.)

To all whom it may concern:

Be it known that I, GUsTAvE DELAY, a citizen of the Republic of Switzerland, and a resident of Le Locle, canton of Neufchatel, Switzerland, have invented a new Process of Hardening and Draw-Tempering Steel, of which the following is a description, and which is applied to all pieces made of steel, and particularly to the small ones used in watchmaking and small machinery.

The pieces to be tempered are placed in a suitable receiver, preferably of iron and of a shape such as a tube, for instance, and'the space between the pieces filled as tight as possible with charcoal-dust. For very small pieces, like those used in watchmaking, a layer of charcoal may be put first into the tube, then some of the pieces, then again a layer of charcoal, &c., until all the pieces are in the tube. The latter is then carefully closed and brought to the suitable temperature-via, to a red heatin an oven or by any other source of heat. When the desired temperature has been obtained, the receiver is opened at one end and the contents thrown into a bath of mineral oil, taking care that the opening of the receiver should dip well in the oil to avoid the contact of the air on the pieces to be tempered before they are cooled off. After the first op eration the tempered pieces must be drawn to give them the necessary hardness. To do that, a paste made of charcoal-dust and mineral oil well mixed must be made and cooked at 300 or 330 and then left to cool off. The tempered pieces are then mixed with the paste in a kettle or other metal receiver, which is placed on the fire with a thermometer dipped into the mixture, and when the height of drawing is reached the receiver is placed into a cold-water bath, taking good care that the water does not get into the paste. Then after this latter is cold the tempered pieces are well washed in petroleum or benzin. Pieces thus tempered are not only extremely well tempered, but also come out of the last operation perfectly white, without any sign of oXid.

In the drawings, Figure 1 is a sectional View of the tube, and Fig. 2 shows a trough with the tube in use. Fig. 1 shows in section the tube A, with cover B, holding the steel pieces to be dipped, such as a c, &c., with the charcoal-dust e. Fig. 2 represents a trough D, in section, filled with mineral oil F, which may be any oil derived from petroleum, into which the open extremity of the tube A dips, while the heated pieces a c, &c., fall into the oil, together with the charcoal-dust, without hav ing been in contact with the ambient air.

The pieces of steel are carried in the tube at a temperature varying from 800 to 900 centigrade, according to the quality of steel and its strength in carbon. The degrees of heat are stated on the centigrade-scale. last heating of the pieces after the bath to bring about annealing varies also according to the hardness to be given the piecesthat is, between a temperature of 220 centigrade which gives the straw-yellow color, and 315 centigrade, which gives the dark-blue glow.

Having now particularly described and as certained the nature of my said invention and in what manner the same is to be performed, I declare that What I claim isi 1. The process of hardening and draw-tempering steel, consisting in heating the same while mingled with charcoal-dust and protected from the air, introducing the same while heated and without exposure to the air into a mineral-oil bath, and then removing from the oil-bath and drawing the temper of the steel by heating the steel While covered by a paste of charcoal-dust and mineral oil, cooling, removing the steel from the paste and then washing in petroleum or benzin, substantially as described.

2. The process of hardening and draw-tempering steel consisting in inclosing the steel pieces in a long tube together with charcoaldust, heating the same while in the tube, placing the end of the tube in a bath of mineral oil, throwing the pieces from the end of the tube into said oil-bath, removing the pieces from the oil-bath and drawing the temper of the pieces by heating them inside of a paste formed of charcoal-dust and mineral oil, removing the pieces from the paste after being cooled and washing the pieces, substantially as described.

In witness whereof I have hereunto set my hand in presence of two witnesses.

GUSTAVE DELAY.

Witnesses:

J ULES CHAPREY, ARMAND TERRELET. 

